Conventionally, as a method of grinding and finishing a gear, a profile grinding method has been provided in which a tooth surface of a gear is finished in form grinding by a grinding wheel. In such profile grinding, a grinding wheel meshed with a gear is first moved in a radial direction of the gear so as to be positioned at a machining start position which is set on an initial cutting position. Then, this grinding wheel is moved in a direction of a rotation axis of the gear (on the initial cutting position) so as to grind one tooth or one tooth space of the gear. Subsequently, when initial (first round) grinding of all the teeth or all the tooth spaces is completed, the grinding wheel is moved from the first cutting position to an inner side in the radial direction of the gear by a predetermined cutting amount. Thereafter, one tooth or one tooth space is ground again. Next, such grinding operations are repeatedly performed until the gear is ground to a final cutting position. As a result, the gear is ground and finished.
In addition, as a method of grinding and finishing a gear, a generating grinding method has been provided in which a tooth surface of a gear is finished by a threaded grinding wheel. In such generating grinding, a threaded grinding wheel and a gear meshed with each other are rotated in a synchronized manner to grind and finish the gear.
Accordingly, as in the case of the profile grinding, in the generating grinding as well, the grinding wheel needs to be meshed and positioned at a machining start position which is set on an initial cutting position, before the grinding. Such a gear grinding method is disclosed in Patent Document 1, for example.